Re: [gpsd-dev] PPS not showing in gpsmon/gpsd on RPi 3

[Eric S. Raymond]

Oliver Jowett <address@hidden>:
> On 23 April 2016 at 11:28, Eric S. Raymond <address@hidden> wrote:
> 
> > gpsd:WARN: KPPS:/dev/pps0 kernel PPS unavailable, PPS accuracy will suffer
> > gpsd:WARN: PPS:/dev/pps0 die: no TIOMCIWAIT, nor RFC2783 CANWAIT
> 
> This looks similar to something I saw a while back where the serial driver
> (a usb-serial driver in my case) did not implement asynchronous
> notifications of handshake line state changes. So neither kernel PPS nor
> TIOMCIWAIT worked. (I never did get PPS working in that case)
> 
> What's the underlying driver for ttyAMA0 on the Pi 3?

I believe it's the vanilla UART driver.  But the HAT only supplies TX/RX,
not the handshake lines.

How it's supposed to work is that the HAT supplies 1PPS to GPIO pin 4,
and the pps-gpio driver turns that into RFC2783 events.  We know this much
is working because ppstest shows them.

I think something about GPSD's setup code for the RFC2783 interface is getting
confused.
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>